The present invention relates to bonders for bonding electronic components such as those with bumps onto target surfaces such as electrodes on a substrate and bonding tools for electronic components.
Ultrasonic press bonding is one of several known methods for bonding electronic components onto target surfaces such as electrodes on a substrate. In this method, ultrasonic vibration is applied to an electronic component while it is pressed against the target surface. Friction generated by minute vibrations of contacting faces results in intimate contact of the contacting faces. A bonding tool used in this method has a horn which is a long thin bar for conveying the vibration of an ultrasonic transducer, the vibration-generating source, to the electronic component. A contacting point of this horn applies load and vibration to the electronic component so as to press and bond the electronic component onto the target surface.
This bonding portion is generally provided at a tip of an element protruding from the horn, in order to avoid interfering with other electronic components, at a part corresponding to the peak where the amplitude is the largest in the horn. Bending vibration, generated by vibration (vertical vibration) conveyed to this protrusion through the horn, amplifies the vibration on a face contacting the electronic component, resulting in bonding of the electronic component.
When the above bonding tool is used for bonding large electronic components, the following disadvantages occur. Displacement perpendicular to the contacting face (in the vertical direction), as well as displacement parallel to the contacting face (horizontal direction), occurs in bending vibration of the protrusion as described above. This displacement increases as the area contacting the electronic component expands. Accordingly, the vertical displacement exceeds a negligible level in the bonding tool for large electronic components.
The vertical load repeatedly applied to the electronic component, as well as the horizontal displacement, risks causing damage to the electronic component. Use of the conventional bonding tool may result in damage to a component during bonding when trying to use the vibration efficiently.
The present invention offers a bonder for press welding an electronic component onto a target face by applying load and vibration to the electronic component. The bonder includes a bonding tool and pressing means to press the electronic component onto the bonding tool. The bonding tool includes a lateral horn supported by a fixed part from both sides; a transducer which applies vertical vibration in a first direction which is a length direction of the horn; a protrusion provided at approximately the center of the fixed part so as to protrude in a second direction approximately perpendicular to the first direction; and a bonding portion provided at the tip of the protrusion which contacts the electronic component. In the bonder of the present invention, the phase of the expansion and compression vibration waveform in the second direction of the horn, which is generated by the vertical vibration, is the same as the phase of a bending vibration waveform at the protrusion generated by the vertical vibration.